The technology development component focuses on four areas which our users have identified as ripe for enhancement: improved accuracy, enhanced imaging capabilities, extension of the charged-particle microbeam to X rays; and development of a simple stand-alone microbeam that can be used without physics support and can be potentially exported to other labs. A highlight regarding improved accuracy and reliability is that we have just received a $2M NIH high-end equipment grant (plus institutional support) for a new particle accelerator, central to the microbeam facility, which will be installed under the auspices of this P-41 grant. Highlights regarding enhanced imaging and sensor technology will be an on-line custom multi-photon imaging system to allow time-lapse fluorescent imaging of early (scale of seconds to minutes) radiation events in individual live cells, a new imaging system based on quantitative phase microscopy to image live cells and cell nuclei without use of potentially cytotoxic stains, and a system for single-cell microsensors to monitor the flux of molecules such as oxygen and NO, in microbeam-irradiated individual cells. In collaboration with a variety of investigators from outside and within Columbia University, 20 collaborative and service-based research projects are described, which both drive and utilize the new resources. All are logical outgrowths of current federally funded research In addition to the ongoing training of undergraduates, graduate students, and post docs, training will be enhanced through formal programs for high school students, high school teachers, and undergraduates. In addition to dissemination of material through talks, our website, and peer-reviewed publications, we will run a 2nd International Workshop "Imaging and Probing Individual Cells: Application to Signaling, Structure and Function", as well as the biannual "International Workshop on Microbeam Probes of Cellular Radiation Response".